Weight compensation device

ABSTRACT

For providing an improved weight compensation for a robot, the invention provides a weight compensation device on a robot, which is characterized by a plurality of parallel tension-proof, pressurized hose elements fixed by their ends to common fixing elements.

FIELD OF THE INVENTION

[0001] The invention relates to a weight compensation device on a robot.

BACKGROUND OF THE INVENTION

[0002] Weight compensation means are provided on a robot, so that themotors for the individual elements only carry out the movement work andonly have to compensate to a limited extent or not at all forces andtorques caused by gravitation. This more particularly applies to therocker of a robot and its movement about the horizontal A2 axis relativeto the robot carrousel and base.

[0003] As weight compensation means have been provided or proposedcounterweights, mechanical springs, fluid springs in the form ofpneumatic and hydraulic cylinders with pistons movable axially therein,magnetic systems, as well as lever and cable systems.

[0004] Each of the known weight compensation means suffers fromdisadvantages. Thus, counterweights require a large amount of space andalso increase the mass and inertia of the overall robot. Mechanicalsprings are relatively large if they are to apply the necessary forcesand consequently have a considerable size. Fluid springs are notmaintenance-free and may require the connection to a pressure medium,e.g. in a pressure container. Lever and cable systems are complicatedand costly. Magnetic systems are also relatively large.

[0005] The problem of the invention is to provide a weight compensationdevice which, whilst avoiding the aforementioned disadvantages andwhilst requiring little space and having a low weight, more particularlyensures a high flexibility in use.

SUMMARY OF THE INVENTION

[0006] According to the invention the set problem is solved by a weightcompensation device on a robot by at least one tension-proof, internallypressurized hose element fixed by fixing elements and where inparticular a plurality of parallel tension-proof, pressurized hoseelements fixed by their ends to common fixing elements are provided.

[0007] Apart from a limited space requirement due to the slenderconstruction provided by the invention the device has a limited weightand is also maintenance-free. It is also substantially free from wear.As a result of the tight construction of the hose elements it can alsobe used in clean rooms. It is also easy to manufacture and inexpensive.Moreover no lubricants are required. In the device according to theinvention high flexibility results from the fact that the length caneasily be chosen as a function of the intended use and the fillingpressure can be easily adapted according to the intended use. As aresult of the slender construction it is also possible to incorporatethe device according to the invention into a rocker or arm of a robot,i.e. it can be incorporated into its carrying elements, such as walls.

[0008] The hose elements provided according to the invention can havenumerous different constructions. According to a preferred developmentthe hose elements have a flexible, gas-tight inner hose andtension-proof fibres surrounding it and the tension-proof fibres are inparticular oriented under a finite angle unequal to 0° with respect tothe hose element axis. Advantageously a fibrous structure is provided inwhich the individual fibres cross one another, so that they have arhombic arrangement. Although not absolutely necessary, according to apreferred development of the invention in addition to the gas-tightinner hose surrounded by the fibrous structure, there is an outer,flexible jacket surrounding both the fibrous structure and the gas-tightinner hose so as to protect them against action from the outside.

[0009] Whilst there are also numerous arrangement possibilities for thehose elements in the device according to the invention, whereby the hoseelements can e.g. be tightly juxtaposed as a group, according to anextremely preferred development the hose elements coaxially surround acentral axis common thereto. According to a further development thefixing elements have plates with which the hose elements are connectedin tension-proof, but detachable manner. The fixing elements inparticular have eyelet attachments for fixing to parts of a robot. As aresult of such fixing elements the device according to the invention canbe easily fixed to parts of a robot and can in particular subsequentlybe detached therefrom. According to a highly preferred development ofthe invention one eyelet attachment is connected to the carrousel of arobot and the other eyelet attachment is articulated to a robot rockereccentrically to its A2 axis.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Further advantages and features of the invention can be gatheredfrom the claims and following description of an embodiment of theinvention with reference to the attached drawings, wherein show: FIG. 1A carrousel and rocker of a robot together with a device according tothe invention.

[0011]FIGS. 2 & 3 Two variants of the coupling of several hose elementsin a hose group corresponding to a section A-A of FIG. 1 viewing inaccordance with arrows A, A.

DETAILED DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 shows the rotary table or carrousel 1 of a robot. Such acarrousel 1 is placed on a not shown robot base and is rotatablerelative thereto about the vertical A1 axis. The rocker 2 is articulatedto a robot carrousel 1 and is pivotable about the horizontal A2 axis ofthe robot at the lower end thereof. A motor is provided for pivoting therocker 2. To ensure that the motor only has to carry out the pivotingwork during the pivoting of the rocker 2 and does not have to completelycompensate the forces or torques caused by gravitation, a weightcompensation means 4 is regularly provided for a robot between thecarrousel 1 and the rocker 2, being articulated thereto eccentrically tothe A2 axis.

[0013] The weight compensation means 4 has, in the embodiment shown, adevice with a plurality of parallel hose elements 6, which arepreferably, as in the embodiment shown, arranged coaxially to an axis Bsurrounding the same. The ends of the hose elements 6 are fixed intension-proof manner to the connection plates 7, 8, which are in turnconnected in one piece or firmly to the eyelet attachments 9, 10. Theeyelet attachment 9 is firmly articulated to the carrousel 1 or aconstructional element 1 a thereof. The eyelet attachment 10 isarticulated to the rocker 2 and, as stated, eccentric to the A2 axis.

[0014] The hose elements 6 have a gas-tight inner hose 6.1, which issurrounded by a rhombic pattern of tension-proof fibres 6.2, which inthe embodiment shown is in turn enclosed by a protective jacket 6.3. Attheir ends the hose parts 6.1 to 6.2 are connected in tension-proofmanner to connecting elements 6.4 and 6.5. One of the connectingelements 6.5 is completely closed. In the case of the other connectingelement 6.4, there is a connection 6.6 for filling the hose element 6.It can consequently be screwed using corresponding screw thread pins tothe connection plates 7, 8 and as a result there is a detachable fixing,so that the hose elements 6 can be released or detached from theconnecting elements 7, 8 again, e.g. for pressure monitoring orrefilling. In the construction according to FIG. 2 the hose elements 6can in each case be individually filled and optionally also with adifferent pressure. An advantage is that in the case of the failure ofone hose the system can still function. However effort and expenditureare higher for individual filling. In the construction of FIG. 3 acommon filling takes place via a connector 6.8, a common inlet 6.7 andthe connection 6.6.

[0015] The hose elements 6 are under an internal pressure and for thispurpose filled with a gas. As a result of the overpressure in theinterior of the hose elements they widen radially and become shorter, asillustrated by the continuous lines in FIG. 2. If a tension is exertedon hose elements 6, if e.g. the rocker is moved out of the verticalposition shown in FIG. 1 into a position inclined to a differing extentto the horizontal, there is a reduction to the diameter of the centralarea of the hose element 6, as illustrated in broken line form in FIG.2.

[0016] The invention gives rise to a low-maintenance and also low-wearweight compensation means, which has limited space requirements and lowweight in the case of high flexibility with respect to the possibleuses, because the filling pressure and length of the hose elements canbe differently adjusted.

1. Device for weight compensation on a robot, characterized by at leastone tension-proof, internally pressurized hose element (6) fixed byfixing elements (7, 9; 8, 10).
 2. Device according to claim 1 ,characterized by a plurality of tension-proof, pressurized hose elements(6) fixed by their ends to common fixing elements (7, 9; 8, 10). 3.Device according to claim 1 , characterized in that the hose elementshave a flexible, gas-tight inner hose (6.1) and tension-proof fibres(6.2) surrounding it.
 4. Device according to claim 3 , characterized inthat the tension-proof fibres (6.2) are oriented to the axis of the hoseelements (6) by a finite angle not equal to 0°.
 5. Device according toclaim 3 , characterized in that the fibres (6.2) are arranged in rhombicmanner.
 6. Device according to claim 1 , characterized in that the hoseelements (6) have an outer, flexible protective jacket (6.3).
 7. Deviceaccording to claim 1 , characterized in that the hose elements (6)coaxially surround a central axis (B) common thereto.
 8. Deviceaccording to one of the preceding claims, characterized in that thefixing elements have plates (7, 8), with which the hose elements areconnected in tension-proof, but detachable manner.
 9. Device accordingto claim 1 , characterized in that the fixing elements have eyeletattachments (9, 10) for fixing to parts of a robot.
 10. Device accordingto claim 9 , characterized in that one eyelet attachment (9) isconnected to a robot carrousel and the other eyelet attachment (10) isarticulated to the rocker (2) of a robot eccentric to its A2 axis.